https://docs.docker.com/engine/install/debian/
Add the docker group if it doesn't already exist:
sudo groupadd docker
Add the connected user "$USER"
to the docker group. Change the user name to match your preferred user if you do not want to use your current user:
sudo gpasswd -a $USER docker
Either do a newgrp docker
or log out/in to activate the changes to groups.
Test docker without sudo
docker ps -a
Source: https://askubuntu.com/a/477554